At the present time, low speed, off-highway vehicles utilize wheel assemblies constructed of steel disc halves that are welded together and employ a one piece steel bearing. The steel bearing must be inserted into the wheel steel disc halves prior to welding the disc halves together and painting. Plastic bushings were not considered practical since the heat generated from welding and painting ovens would exceed the melting point of most plastic materials. These prior art wheel assemblies for the off-highway vehicles require steel tubing for receiving the bearing and a grease zerk. Accordingly, there is a present need for a plastic bearing to be used on the low speed, off the road vehicles that can be readily mounted to the wheel assemblies for such vehicles after the assembly operations requiring high heat are completed.
Various types of plastic bushings are presently known in the art. A one piece bearing support bushing is disclosed in U.S. Pat. Nos. 3,438,686 and 5,145,265. These one piece plastic bushings are designed to permit them to be compressed for mounting in the base of a workpiece or bearing. Two piece plastic bushings are disclosed in prior U.S. Pat. Nos. 2,797,605, 3,091,795 and 4,883,319. U.S. Pat. No. 2,797,605 discloses a two part fastener that is constructed with shanks having a plurality of sections spaced longitudinally thereon for receiving the shank sections of the other element and adapted to be locked together in a bore. U.S. Pat. No. 3,091,795 discloses a grommet of two piece construction mountable from opposite sides of an opening in a panel, while U.S. Pat. No. 4,883,319 discloses a self-locking, plastic spacer bushing for use in a hinge for an automotive vehicle seat assembly consisting of identical inter-locking sleeves. The sleeves are thin walled and cannot carry a substantial radial load; see Col. 3, lines 51-57. None of these prior art bushings are useful in the wheel assemblies for low speed, off-highway vehicles such as wheelbarrows and hand trucks or the like.